3
The top look like this:
KiB Mem : 3989652 total, 30976 free, 1480440 used, 2478236 buff/cache
KiB Swap: 0 total, 0 free, 0 used. 2276236 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3989 root 20 0 51680 3160 1288 D 19.8 0.1 13:13.86 mc
5949 root 20 0 0 0 0 D 3.6 0.0 41:33.92 [usb-storage]
667 root 20 0 0 0 0 S 1.0 0.0 8:37.38 [kswapd0]
I turned off swap intentionally. The output like above was captured several minutes after the "KiB Swap total" turned 0. There is a running process which copies from NFS share to USB hard drive (that is mc)
kswapd keep using around 1% of CPU time. Why?
1In other words, kswapd serves not only RAM extension aka "the swap", but also mmap and other memory paging related features in linux. – Nikita Kipriyanov – 2016-09-14T05:57:49.187
@NikitaKipriyanov: That's right. – Zaz – 2016-09-16T07:25:47.263